Antagonistic Activity of Bacteria Isolated from the L. Gut against Some Multidrug-Resistant Human Pathogens.

The insect gut is home to a wide range of microorganisms, including several bacterial species. Such bacterial symbionts provide various benefits to their insect hosts. One of such services is providing metabolites that resist infections. Little data are available about gut-inhabiting bacteria for several insect groups. Through the present work, the gut bacteria associated with the American cockroach ( L.) were isolated, identified, and studied for their potential antimicrobial activity against multidrug-resistant (MDR) human pathogens. The cockroaches were collected from three different environmental sites. Gut bacteria were isolated, and sixteen species of bacteria were identified using Vitek MALDI-TOF MS. The antagonistic activity of the identified bacteria was tested against a panel of multidrug-resistant bacteria and fungi, namely: methicillin-resistant (MRSA) (clinical isolate), Clarke (RCMB 017(1) ATCC 25175™) (Gram-positive bacteria), (RCMB 001(1) ATCC 23355™) and (ATCC 25566™) (Gram-negative bacteria). The isolates were also tested against human pathogenic fungi such as (RCMB005003(1) ATCC 10231™), (RCMB002005), (RCMB002008), (RCMB002002), and (RCMB 001018(1) IMI193019). The results indicated that some bacterial species from the cockroach gut could antagonize the growth activity of all the tested pathogens. Such antimicrobial properties could ultimately lead to the future development of therapeutic drugs. The evaluation and mode of action of antagonistic gut bacteria against the most affected MDR pathogens were demonstrated using transmission electron microscopy (TEM).